Pipeline “pigs”, which may alternatively be referred to as pipeline inspection gauges, or pipeline inspection gadgets, are devices that are placed inside of a pipeline to traverse and inspect the pipeline. Pigs may be used in pipelines and subsea pipelines to conduct hydrostatic testing, to conduct cleanup operations, to conduct batch transportation operations, to prevent solid accumulation and corrosion, to apply coatings, and to conduct inspections.
In hydrostatic testing, a pig may be inserted into a pipeline ahead of a fill point, and the pipeline may be filled with water behind the pig. In this manner, the pig may be used to fill the pipeline without entrapping air, and, subsequent to testing, to remove the test waters and to dry the pipeline.
In cleanup operations, a pig may be used to clean solids, scale, wax buildup (paraffin), and other debris from a pipeline wall to keep the line free of occlusions and debris. In batch transportation, pigs may be used as a separator to keep separate batches of product that are being transported by the pipeline. Such products may include gasoline, diesel fuel, fuel oils, and other products.
To prevent accumulation of solids and corrosion, pigs may also be used in crude-oil pipelines to keep water and solids from accumulating in low spots. In addition, in coating operations, pigs may be used to apply internal pipe coatings, such as epoxy coating materials, in operating pipelines. Pigs may also be used to coat the pipeline with corrosion inhibitors.
In addition to the foregoing uses, pigs may also be used as inspection tools. To that end, a gauging or sizing pig may be following a new construction or line repair to determine if there are any internal obstructions, bends, or buckles in the pipe that might merit further repair. A camera may be attached to a pig to allow for visual inspection of the internal surfaces of the pipeline. Pigs may also be outfitted with magnetic and ultrasonic systems that locate and measure internal and external corrosion pitting, dents, buckles, and any other anomalies in the pipeline wall.
The illustrated figures are only exemplary and are not intended to assert or imply any limitation with regard to the environment, architecture, design, or process in which different embodiments may be implemented.